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New Dynasty 350 Arc Instability Problems

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  • New Dynasty 350 Arc Instability Problems

    First time poster here on this forum but long time welder.

    So, the Co. I work for just got a brand new Dynasty 350. Its a machine that I'm pretty familiar with and have welded with them quite a bit. Everything seems to work just fine but I keep noticing that the arc really wants to jump around and I've never had this problem with other Dynasty's.


    6061 Aluminum 3/8" to 3/4" T-Joints (Prepped with aluminum cleaner then brushed to death with a stainless brush to break through the aluminum oxide)
    1/8" Zirconiated Tungsten ground just like Miller recommends in the manual.
    Usually 100% Argon at 25 - 30 CFH (Sometimes I'll mix a little He in for the thicker material)
    Water Cooled 350A torch w/gas lens


    Continuous HF
    Max Current: 350
    AC Balance: 75%EN
    AC Current Differential: Even
    Waveshape: Soft Squarewave
    AC Freq: 150 - 250 (depends on how I want the arc focused)

    At arc start it usually starts at nearly a 90 degree angle away from the tip of the tungsten but as more current is applied it will snap back to center for a fraction of a second and then jump to the other side. However, on T-joints (which is what I have to weld mostly) the arc will snap back and forth between the vertical and horizontal parts of the joint. No matter how hard I try to get the arc to just run into the root of the joint it will not do it. It reminds me of arc blow when stick welding in DC with a coiled up ground lead.

    I've tried adjusting AC Freq, I've tried different tungsten, different grind profiles, checked my ground etc. I usually use Ceriated tungsten with inverter TIG machines but this Co. has yet to get me any. I suspect that its the tungsten. I have never had this much trouble with any TIG welder.

    Also, no matter how much EN balance I put into the settings my tungsten balls up like crazy and gets into the puddle causing contamination as if I were running more on the EP side of the wave but I know I'm not. I've checked my settings a dozen times and even moved to a different memory location and started dialing it in from scratch.

    Anyone have any ideas? Feeling a little stupid here. Gotta be something simple that I'm overlooking.

    Thanks in advance for your input.